750ti Throttling

i used to use precision x to slightly overclock this card and i noticed it started deeply under-clocking my card. I was playing rust and i guess precision  x thought rust didnt need any graphics card power so my clock was around 400 when this card can be easily overclocked to 1200mhz. Now i'm using asus gpu tweak and it was ok for a while but then its started throttling again, the temperature is not the problem i think, because its around 25 Celsius when playing a game. How can i stop this throttling, Thanks!

my understanding is that once an NV card detects a power instability, it will throttle to near idle clocks to prevent damage and won't go back up until reboot. lower the OC, or run stock clocks.